The present invention is related to mobile wireless communication systems and more particularly to core networks for such mobile wireless systems.
Wireless communication systems typically include both a radio access network that provides connectivity to mobile stations and a backbone or core network that interconnects radio access points and provides connectivity to wireline networks such as the public switched telephone network (PSTN). In so-called second-generation systems, the radio access network portion is based on a digital mobile wireless communication standard such as GSM, IS-95, TDMA, etc. These standards are primarily oriented towards voice communication. The geographic area to be covered is divided into a number of cells, each cell being equipped with one or more base stations.
A mobile switching center (MSC) connects the public switched telephone network to a radio access network (RAN) linked to the base stations. One of the tasks of the MSC is to manage the wireless connection. This includes handling hand-offs, both between RANs or cells controlled by an MSC and to and from RANS or cells controlled by other MSCs, handling roaming, and providing a connection to and from the PSTN. The MSC is also responsible for handling call management including the signaling and call control functions to set up and tear down mobile originated calls, set up and tear down mobile terminated calls, and handled advanced calling features such as call waiting, call forwarding, etc.
Mobile wireless communications systems are now in the process of transitioning to a third generation. In a third generation wireless system, the radio access network is typically based on UMTS (the Universal Mobile Telecommunications System defined by ETSI) or the CDMA2000 standard (defined by TIA/EIA) and has been optimized to handle both voice and data. The core network is often based on IP and can provide connectivity to both the PSTN and the Internet. Simultaneously, voice telephony is undergoing its own transition from a circuit switched architecture where connection control systems, call control systems, and other services interact via proprietary interfaces in TDM switches to an open packet telephony model where services, call control, and connection control are handled by different entities that interact via interfaces specified by open standards.
There is a need for an architecture that performs the functions of the MSC of prior wireless communication systems while taking advantage of the flexibility provided by IP based core networks and packet based telephony.